In the past, various kinds of foods such as confectionaries or breads are produced using egg whites having a certain foaming property. The foaming property of egg whites largely affects the leavening degree, smoothness, texture, and the like of such foods, the foaming property being indicated by stiffness and other properties of foam.
There are known various kinds of factors that decrease the foaming property of egg whites. A main factor is egg yolks admixed in egg whites, for example. Egg yolks may be admixed in egg whites unavoidably when mechanically breaking shell eggs on the industrial scale and separating egg yolks from egg whites.
Further, it is known that the foaming power of egg whites is further decreased after egg whites are frozen, the egg whites being obtained by mechanically breaking shell eggs and egg yolks being admixed (see Non-Patent Literature 1).
Meanwhile, in the field of frozen foods, it is generally known that, when freezing foods where the transit time of the temperature zone from −1° C. to −5° C., i.e., a so-called the maximum ice crystal generation temperature zone, is long, large ice crystals are formed and therefore tissues of foods are highly likely to be broken. In view of this, so-called rapid freezing, in which the transit time of the temperature zone from −1° C. to −5° C. is short, is recommended when freezing foods to produce frozen foods.
Similarly, when producing frozen liquid egg whites, it is understood that the freezing condition, in which the transit speed of this temperature zone is high, is preferable in order to minimize damage of egg whites due to freezing and in order to keep the condition of defrosted frozen liquid egg whites similar to the condition of unfrozen liquid egg whites.
Meanwhile, for example, Patent Literature 1 discloses a method for adding and mixing β-cyclodextrin in an example in order to prevent a foaming property from being decreased due to egg yolks. It is known that this method has some, but inadequate, improvements in a foaming power (see result of Comparative Example 4 of the present description).